Non-aqueous electrolyte secondary battery

Abstract

A negative electrode material mixture with a negative electrode active material including a Si-containing material and a carbon material; and a carbon nanotube. The Si-containing material includes, a first composite material in which Si particles are dispersed in a lithium silicate phase and/or a carbon phase, and a second composite material in which Si particles are dispersed in a SiO2 phase, at least the first composite material. A mass ratio X of the first composite material to a total of the first and second composite materials, and a mass ratio Y of the total of the first second composite materials to a total of the first composite material, the second composite material, and the carbon material satisfy a relational expression (1): 100Y−32.2X5+65.479X4−55.832X3+18.116X2−6.9275X−3.5356<0, X≤1, and 0.06≤Y. The non-aqueous electrolyte includes LiPF6 and LiN(SO2F)2.

1 . A non-aqueous electrolyte secondary battery comprising:
 a positive electrode; a negative electrode; and a non-aqueous electrolyte,   wherein the negative electrode includes a negative electrode material mixture including: a negative electrode active material including a silicon-containing material and a carbon material; and a carbon nanotube,   the silicon-containing material includes, of a first composite material and a second composite material, at least the first composite material,   the first composite material includes a lithium ion conductive phase, and silicon particles dispersed in the lithium ion conductive phase, the lithium ion conductive phase including a silicate phase and/or a carbon phase, the silicate phase including at least one selected from the group consisting of alkali metal elements and Group 2 elements,   the second composite material includes a SiO 2  phase, and silicon particles dispersed in the SiO 2  phase,   a mass ratio X of the first composite material to a total of the first composite material and the second composite material, and a mass ratio Y of the total of the first composite material and the second composite material to a total of the first composite material, the second composite material, and the carbon material satisfy a relational expression (1):
   100 Y− 32.2 X   5 +65.479 X   4 −55.832 X   3 +18.116 X   2 −6.9275 X− 3.5356<0,
 
     X≤ 1, and 0.06≤ Y , and
 
   the non-aqueous electrolyte includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide: LFSI.   
     
     
         2 . The non-aqueous electrolyte secondary battery according to  claim 1 ,
 wherein the mass ratio X and the mass ratio Y satisfy a relational expression (2):
   100 Y− 2.1551×exp(1.3289 X )<0,
 
     X≤ 1, and 0.06≤ Y.  
 
   
     
     
         3 . The non-aqueous electrolyte secondary battery according to  claim 1 ,
 wherein the carbon material includes graphite.   
     
     
         4 . The non-aqueous electrolyte secondary battery according to  claim 1 ,
 wherein a content of the carbon nanotube in the negative electrode material mixture is 0.1 mass % or more and 0.5 mass % or less, relative to a whole of the negative electrode material mixture.   
     
     
         5 . The non-aqueous electrolyte secondary battery according to  claim 1 ,
 wherein a concentration of the LFSI in the non-aqueous electrolyte is 0.2 mol/L or more.   
     
     
         6 . The non-aqueous electrolyte secondary battery according to  claim 1 ,
 wherein a concentration of the LFSI in the non-aqueous electrolyte is 0.2 mol/L or more and 0.4 mol/L or less.